Abstract To accurately predict indoor air moisture levels, the input data that includes the moisture production must be determined with high accuracy. The existing researches provide data about the estimated moisture generation rate by household activities but the data vary largely between the publications. Therefore, during this research, measurements of moisture generation from sources like cloth washing, emission by plants and human respiratory process were carried out. The moisture production in case of natural cloth washing and drying in indoors was performed in household environment at different mechanical washing machine drying revolution speeds and for five pieces of typical clothes. Also the influence of mechanical washing machine drying revolution speed as well as clothing fabric was determined. The moisture production from plants and humans was measured in climatic chamber with controlled environment by calculating it according to measured relative humidity. The overall results showed inconsistency with the ones provided in existing researches. The obtained moisture production values were lower for each of the source. This findings can be applied in future calculations when predicting indoor humidity.